Marine inorganic calcium carbonate precipitates occur in three varieties or polymorphs, low Mg calcite, high Mg calcite and aragonite. This study deals with High Mg calcite and aragonite and indicates that the calcite lattice structure is affected by varying Mg/Ca ratios and its precipitation rates slow down with increasing Mg/Ca ratios. It can maintain a particular rate of precipitation only by increasing the CO3 saturation state of water. The aragonite lattice is not hindered by the presence of Mg and as a result aragonite might well be the dominant inorganic precipitate at higher Mg/Ca ratio of seawater.

I don't have access to the full paper so this is not a review but I since I have been working with carbonate cements I ended up thinking about the practical problems of recognizing cement mineralogy in ancient carbonates.

Let's take a step back. The three calcite polymorphs don't occur with equal abundance through geological time. Sea water chemistry has fluctuated from calcite seas where low Mg calcite has been the stable inorganic precipitate to aragonite seas where increased Mg/Ca sea water ratio resulted in aragonite and high Mg calcite becoming more abundant. These trends apply only to inorganic precipitates. Organisms that use one of the three polymorphs to build skeletons don't switch between the varieties if sea water composition changes. There are very conservative about which latticeware they drape themselves in.

If Mg/Ca ratios play a role in controlling rates of CaCO3 polymorphs, can we recognize trends in abundance of aragonite vs high Mg calcite in carbonate sequences. I am thinking of scenarios which could produce such trends. Carbonate sediments accumulate as thick piles often hundreds to thousands of metres thick. These piles of sediments are not homogeneous mixtures of sediment but are layered and there is a particular architecture to this layering which reflects the rise and fall of sea level. An initial rise in sea level will produce environments of deposition with considerable water depths and good circulation of sea-water throughout the depositional system. At this point in the history of the platform - known as transgressive systems tracts- tidal flats have just about nucleated along shorelines, reefs have begun aggrading but have not developed a distinct profile. The Mg/Ca ratios and saturation levels of sea-water would promote both aragonite and high Mg calcite cements in varying subenvironments.

But later as sea-level rise peaks and then starts to fall - known as highstand systems tracts followed by the beginnings of a lowstand systems tract - the distribution of facies in this deposition systems has changed. Tidal flats prograde over large expanses of the platform. Reefs have a topography that acts as a barrier to currents and produces quiet back lagoon environments with restricted circulation. Overall in this mature stage of sequence development there are larger pockets of evaporative environments and very high Mg/Ca ratio of sea-water. Does that lead to more aragonite precipitation as high Mg/Ca ratios becomes a kinetic barrier to calcite precipitation?

This was my speculation but I haven't come across studies which try to assess the relative abundance of these two carbonate polymorphs across any one platform and sequence history. Maybe no one is interested but a more practical reason is the extreme difficulty in identifying and quantifying ancient marine cements.

Both aragonite and Mg calcite are unstable in fresh water. Sooner or later carbonate sequences are exposed to meteoric diagenesis and these two carbonate polymorphs are altered to low Mg calcite. The change is often fabric disruptive, meaning even the original distinct morphology of marine cements - acicular, bladed, elongated - is lost.

This is where a second study reported in the latest issue of Sedimentology gives hope to researchers interested in understanding ancient marine cement distributions. This piece of research compares the rare earth element (REE) composition of unaltered aragonite coral skeletons with the REE composition of their altered counterpart i.e. low Mg calcite in the same reef. So what has happened is that a Pleistocene reef has been incompletely altered to low Mg calcite giving researchers an opportunity of understanding how REE composition changes as aragonite alters to calcite.

And they find that unlike minor elements like Sr, Ba, U which are lost from the aragonite lattice and are not incorporated in the newly forming calcite, the REE are conservative and are retained in almost the same proportions in the new diagenetic calcite as they existed in the precursor aragonite.

The study does not include original high Mg calcite so what has this to do with trying to quantify ancient ratios of aragonite to high Mg calcite in carbonate sequence?

I would be willing to put up a small wager that there is a systematic difference in the amount of REE the aragonite lattice can incorporate versus what a high Mg calcite lattice can. Aragonite is orthorhomic and generally accepts more easily large ions (ion size similar or larger than Calcium) like the REE in its lattice. Calcite cannot readily accept such large ion sizes in its trigonal lattice. Since the original REE distribution may be preserved in later diagenetic products, it may just be possible to tease out the original relative proportions of aragonite vs high Mg calcite cements in ancient sequences.

As an aside the use of rare earth element geochemistry has a long tradition in sedimentary geology, but it has been used in clastic sedimentary geology for provenance analysis much before its use in diagenetic studies. REE patterns in crustal rocks from different tectonic provinces are distinct. So mature craton versus forearc versus recycled orogen may be differentiated by REE composition of their detritus. Their use in carbonate diagenesis is a relatively recent development and given the complicated diagenetic histories of ancient carbonates, a very welcome addition to the carbonate geologists toolkit.

Thursday, July 23, 2009

This project initiated by the Central Government to create a city level Geographic Information Systems (GIS) database for 152 cities and towns all over India has a lot of merit. If implemented to its full potential by individual cities, it could knock some sense in the day to day governance of Indian cities and help prepare for their planned growth.

GIS for urban applications has lagged behind GIS for natural resource application in India. There are probably many reasons for this. Institutional inertia, lack of awareness, inadequate city budgets and the high expense of creating detailed spatial datasets; all these or different combinations of these factors in different cities have prevented GIS from playing a constructive role in city planning.

The National Urban Mapping Mission looks to change all this. Funding for developing 1:10,000 and 1:2000 scale spatial datasets will be provided by the Central Government (75%) and the State Government (25%). The Survey of India which is the National Mapping agency will take charge of data creation. There will be deadlines, timelines, capacity building , performance measures... all the corporate buzzwords for successful project management are being pressed into service. The end result will be seamless city level spatial datasets, all relevant information needed to run the city just a mouse click away.

I'm excited about this mission. The experience of using GIS for city planning in Pune where I live has been to put it mildly ... disappointing. There have been various half hearted attempts to use the technology, but the mentality has been to use it to solve isolated problems. There hasn't been a concerted effort to create an integrated city level system which brings together data from various departments and then crucially to embed this GIS in the day to day work schedule of the city government.

And it is the way in which individual cities respond to this initiative that offers the greatest potential for success but also possible stumbling blocks to its effective implementation. Despite this impressive start I have to express my concerns over the long term viability of the National Urban Mapping Mission. I looked through the roadmap document available through their website. It is impressive. There is no question that the Survey of India is a reputable organization and a high quality database will be developed by them. Also importantly there is money set aside for capacity building. Each city will send a few officials to get trained in GIS.

What I want to know is whether individual cities will set aside money from its budget to fund a full time specialist staff to manage this GIS. Over the long term the responsibility of maintaining this GIS will have to come from within the city government budget. The Centre and State are unlikely to contribute any money towards hiring staff and other such sundry city governance matters. So far the way to avoid hiring additional staff has been to delegate GIS as an additional responsibility to city engineers and planners who have ten other matters to attend to.

This could work in the past because GIS played a minor role if at all in city planning. But if these soon to be available new massive datasets and attending software and hardware are to be looked after properly and used to their fullest potential, then specialists will need to be hired full time. Surrogates who will be spending most of the day in their primary job as a city engineer or planner or administrator simply won't be able to act as GIS gurus as well.

I have come across this situation before with the Maharashtra Forest Service. A few years back I had a conversation about GIS with a forest officer. He was frustrated that after spending tens of thousand of dollars on GIS software, the Maharashtra Government made no provision to hire specialists to run it! Instead Forest Officers were sent for training. Now, these are smart officers but their primary duty was to tour the district, make working plans for forest management and attend to other administrative tasks. They had no time left over for GIS work.

This Urban Mapping Mission has been to some extent forced upon cities by the Central Government. But such a top down approach is handicapped by the fact that the Central Government doesn't run the cities. The success of this mission will depend upon whether individual city governments allocate sufficient funding to and allow GIS to play a central and integrative role in the process of city management and planning. Many cities have created good development plans for growth without the use of GIS over the years. But political interference and pressure from the urban builder lobby has seen those plans fail. Technology by itself will not fix the misgovernance of Indian cities. Using GIS effectively means a change in mindset first. Given the chaotic and corrupt history of functioning of Indian city governments there is reason for some pessimism here.

The second question I had was about citizen access to all this data. Will these datasets eventually become part of the National Spatial Data Infrastructure? Will they be available to citizens for download (don't mind paying for them, I am not asking for free data, just easy access to it) thus enabling value additions that will encourage a thousand spin off applications to emerge?

That would be the forward looking and mature position to take. I hope our government thinks the same.

Thursday, July 16, 2009

Not even Intelligent Design (ID) proponents would have used as argument as dumb as the one the writers of the TV show Boston Legal did recently.

I caught only part of the show a couple of days ago, fortunately the part where the judge is ruling on whether ID should be taught along with evolution in biology classes. The defendants are members of school boards who want ID to be taught. The State is against the idea and is prosecuting.

Not verbatim but the ruling went along something like this:

Judge: I've heard all the arguments. Now.... its clear that religious beliefs should not interfere with a secular education...

Judge: ...But its also clear to me that secular eduction should not completely erase the role of religion in our lives...

Prosecutors shake heads with an air of resignation, Defendants look much more cheery..

And then this eye popping piece of legal reasoning..

Judge: Haven't all of us wondered at one time or the other...don't we all have a sense of wonder and awe when holding a new born baby that there must be something more to life .. a higher mystery... than science can explain.... So I am ruling that ID should be taught alongside evolution... Case dismissed!!

Off course this fictitious case gives a ruling exactly opposite to the one where ID suffered a crushing defeat in court some years ago. In that ruling Judge John E. Jones III made it clear that ID is a lovechild of religious parents, a descendant of creationism, and is not a scientific theory and cannot be taught in evolution classes. His rejection of ID did not depend on whether science explains everything or not. In fact he makes it clear that the theory of evolution does not rule out the presence of the Almighty.

But Judge Jones said...well he didn't exactly say it, I am saying it ... but he ultimately meant ...

That while it is possible that holding a bald, slippery and naked baby may invoke a sense of mystery and awe in some of us, and a feeling that science does not explain everything about life, that does not qualify as a reason to include ID alongside evolution. A sense of mystery and awe are not scientifically testable alternative explanations of life. In other words ID besides saying that evolution cannot explain this or that doesn't offer any positive solution to the problem.

Television networks are ruled by ratings and they would have calculated that a show in favor of religious views over evolution would be approved by lots of American viewers. ID proponents have been over the years distancing themselves from making any overtly religious or mystical arguments like the one in this show since they want to be seen as "scientists". They would positively avoid any mention of religion when making their case. But the writers of the show inadvertently revealed their true motives.

I am reading The Ruling Caste: Imperial Lives in the Victorian Raj by David Gilmour. It's an account of the day to day lives of British Civil Servants as they went about their administrative duties in 1800's India. The District Collector was one of the key positions - as it is today- and the Collector besides his responsibility as a revenue officer was also a Magistrate who heard cases and imposed fines up to Rs 1000/- and sentences of up to 2 years:

The Collector and the Magistrate had many different functions, but for his main two he also possessed different personas. He had separate offices for them , staffed by separate sets of clerks who enjoyed acrimonious correspondence with each other. One District Officer "used to find drafts of letters from myself as Magistrate to myself as Collector accusing myself of neglect and delay, and some very trenchant replies placed before me for signature".

Among the many responsibilities and expertise the Collector had to acquire was an ability to understand landscapes and read maps. Assessing property holdings and estimating tax was a tricky task and the land holdings were drawn on enormous pieces of linen with parcels shown at a scale 1 mile to 63 inches! That means over 5 feet of cloth was used to depict one mile of the earth.

These were local maps covering only one village and surrounding area and showing only property holdings. A much larger mapping effort to produce a seamless tapestry of the Indian landscape- also initiated by British geologists and surveyors- was going on in the 1800's, one that very carefully was measuring the lay of the land and producing a triangulation network which later survey projects used as the basis for generating topographic maps on a scale of 1 inch to 1 mile. That effort is described in The Great Arc by John Keay. It is an absorbing and startling account of a mapping project that lasted half a century and produced the baseline landscape information that were then used for additional survey, building roads, canals and railways.

Indians reading the Ruling Caste might feel that the book is perhaps too sympathetic towards the officers of the Civil Service. They were after all men carrying out the orders of a colonial exploitative regime. But the job was a genuinely tough one. A person with no experience of India at age 23 was suddenly given charge of as many as 2 million people. An Officer could be stuck at a remote station with no correspondence with headquarters for weeks. Decisions had to be made on the spot that could influence the lives of thousands.

The Civil officers or "Civilians" were always outsiders amongst what seemed a strange and bewildering people, yearning for "Home" and waiting eagerly for Furlough ( a two year sabbatical in England). But tragically they were strangers too when they went back to England on retirement. Most of them missed India on their return to England, missed the outdoor life and the responsibilty of office and the servants- in-waiting. And after a 30 year career they found that people in England regarded them to be bores too eager to tell India stories and completely out of touch with contemporary England society.

Rudyard Kipling famous for his evocative descriptions of the Raj despaired on being confronted with the dreary London sky-

It's Oh to see the morn ablaze

Above the mango-tope

When homeward through the dewy cane

The little jackels lope.

And half Bengal heaves into view,

New-washed - with sunlight soap.

If you read this book as a human interest story you will find it rewarding.

Thursday, July 9, 2009

I noticed this story a couple of days ago and finally an email exchange with friends on the meaning of adaptation, fitness and success prompted me to write this.

The basic story is that the harsh winters of the St Kilda archipelago beyond the Outer Hebrides have been favoring sheep which grow faster and get bigger during the summers. In winters that big size is an advantage due to higher stored fat content. Smaller sheep - those that develop slower in summers - are at a disadvantage in these conditions and die off disproportionately. Recently though researchers have noticed that the population is shrinking in terms of the size of individual sheep. Smaller sheep are surviving in larger numbers. The reason could be climate change and warmer winters.

This has led to speculations that climate change has overridden natural selection.

That's just wrong. Climate change has not overridden natural selection. It has shifted the selection pressure on the sheep population. Under the previous climatic regime smaller sheep were at a disadvantage i.e. they were under negative selection. That negative selection has been eased off due to the recent warmer winters.

Classical evolutionary theory suggests that over time the average size of wild sheep increases, because larger animals tend to be more likely to survive and reproduce than smaller ones, and offspring tend to resemble their parents.

This makes it seem as if there is some universal process that will develop trends towards larger size. "Classical" evolutionary theory says no such thing about populations getting bigger in the size of individuals as an inevitable outcome. It may just so happen that for a particular time period the conditions - like harsh winters- favor bigger animals and a trend develops in a population towards larger size. But that can just as easily be reversed if conditions change and start favoring smaller size. A trend towards smaller size is also predicted by the same "classical" evolutionary theory.

Headlines like survival of the less fit perpetuates the misconception that in evolution bigger or stronger is better. We can do without such thinking.

Tuesday, July 7, 2009

Natalie Angier has an article in the NYTimes on the treasures being unearthed by the massive Panama Canal Expansion project. Teams of geologists and palaeontologists are getting access to fresh exposures that are usually not available in the thickly forested and deep soil tropical areas. Panama geology is very tricky, fragments of several plates have been plastered together over the eons to create a mishmash of terrains and new deep exposures will help in gathering data and improving understanding of Panama's dynamic history.

These days, Mr. Rincón and scores of other scientists are digging as fast as they can in the shadows of the really big dig that is the Panama canal expansion program, the most ambitious overhaul to the complex array of locks, channels, dams and bridges since the canal was built a century ago.......

.....Speed dating for scientists has already borne fruit. Through analyzing more than 2,000 fossils, the stratigraphic record revealed by each new rock cut, paleomagnetic data, isotope ratios, carbon signatures and more, researchers are getting a sense of what an ancient tropical rain forest looked like.

There has been a long history of spinoff's for geologists from major engineering projects. Way back in late 1700's England, canal builder William Smith was inspired by the geology exposed along the new canals which were being built to transport materials from factories to markets. He then embarked on his epic mapping project of England, an endeavour that virtually formalized the science of mapping and geology.

Engineering projects of this scale do reveal the hidden geology by exposing previously inaccessible areas or depths but there is a downside to this. Many times it is hard or downright impossible to revisit these outcrops again. With the Panama situation these outcrops will be drowned once the canals are completed and adjacent slopes being reforested will make working conditions in the viscinity of the canals difficult in the few years. So this is a grab-while-you-can situation for the scientists present but with no provision for a second look for validation.

This is going to be a good test I feel of the methods and technology being brought to bear on creating an accurate and representative archive of Panama geology. There will be records available through photos, outcrop descriptions and samples (willgigapanshelp? ). But nothing beats having the actual outcrop in front of you.

That option which has fortuitously opened up for scientists is going to be lost soon.

Wednesday, July 1, 2009

Environmental Impact Assessement (EIA) reports are a requirement for clearing big development projects. India Together has an eye-opening article by Shripad Dharmadhikary on how this process has been subverted by the government and relegated to a side show... a mere rubber stamp for official project clearance.

First and foremost, the basin studies have been effectively de-linked from the implementation of the projects as there is no requirement that the projects be conditional to the findings of the basin studies. Neither is there any explicit stay on the consideration and implementation of any of the projects pending the studies.

Logically, the basin studies should suggest what level of development, including hydro power projects, the basin can sustain. The projects should be planned based on this. However, the current planning and decision making turns this on its head. The numbers, locations, capacities, types and other details of the projects have already been decided. Many of these projects have already been allotted to (mostly) private developers who already have or would soon be approaching the Ministry for environmental clearance. In Bichom basin, the 600 MW Bichom (or Kameng) project is already under construction.

Assessment studies for big projects can take up to 2 years but this time period for many projects is reduced to just 6 months. And often the studies themselves are superficial .."farcical" according to the article.

That could happen for a number of reasons:

1) The Terms of Reference are crafted in a way that make any coherent analysis impossible.2) The consultants hired to carry out the EIA are of poor quality.3) The consultants / scientists know that their work and recommendations will not have any significant impact on the project details since the government has already decided what to do. So they have no real incentive to produce good work.

To me the last one is the most depressing of all. As a working scientist I would hate to be in a situation where I know in advance that my work will not be treated with respect and will make no difference as a practical matter.

Despite all the big talk from the government about the prime position of science in society examples like this one does not inspire confidence in the government's attitude towards the role of science in charting India's development. Talk is cheap but actions speak to the real intent. By these actions the government seems to be saying ..Oh you can have your little science project on the side.. but don't bother us with the details.

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ABOUT THIS BLOG

I am a Sedimentary Geologist. On Rapid Uplift I write mostly about topics within the geosciences, but sometimes on biological evolution and environmental issues. I like to travel and in my free time I teach 12 year old kids soccer and rugby.